Latest test of SpaceX Grasshopper adds a twist

The prototype flies laterally before coming back down.

The latest test of the SpaceX vertical takeoff and landing rocket prototype didn’t take it any higher than it went on the last two flights, but it added a degree of difficulty that could impress even the most disapproving Russian judge. The 32-meter-tall rocket ascended 250 meters while also travelling 100 meters laterally away from the launch pad before maneuvering back and setting itself gently down on the pad. This is the first test flight to include a lateral component.

The vertical landing technology is being developed to make the Falcon 9 and Falcon Heavy rockets rapidly reusable. After doing its portion of the heavy lifting, the first stage of the rocket would bring itself right back to the launch pad rather than splashing down in the ocean and awaiting recovery. The second stage would do the same after placing the payload in orbit, a preferable outcome to letting it burn up on reentry.

Seriously, SpaceX blows my mind, again. They put the traditional American aerospace industrial operators to *shame*, not merely by the scope and scale of their achievements but further by the speed with which they have made these accomplishments. They make it look easy, and they do it for pennies on the dollar.

Seems like instead of a powered descent they could use a parachute with a few small jets active to steer which would use much less fuel.

Edit to add: that said -- this is amazing and one of the most amazing things i've seen. Seeing the rocket hover, and then start to tilt was SO close to the sequence some other rockets have gone through just before catastrophic failure that I was literally on the edge of my seat. Fun!

Isn't it still much more expensive to land that thing than to just to let it burn up, or to retrieve it from the ocean?

I have no idea, but cheap isn't what they're aiming for. This is purely about being able to get the next payload up and in orbit as fast as possible. When each launch requires a complete rebuild of the entire rocket system, that's downtime, or complex production logistics.

It may waste fuel, but that's really not the point. It's often very effective to do impractical things as proof of concept to help you better understand some of the practical things you want to accomplish.

It's tough to get a real sense of the lateral component of the test flight from the video. Particularly since the camera pans away and no ground is shown for reference.

Half way through the article, I was thinking it was going to land on a DIFFERENT pad. Scott did clarify by the end, so the video wasn't a surprise. Still wish it had landed somewhere else. Obviously there is no technical advantage whatsoever in terms of validation (state function), but the WOW factor is much higher with the path function.

Wow, I am amazed that people suggesting the fuel costs less than the rocket are getting downvoted out of hand.

I didn't know the numbers, but it seemed absurd to suggest the fuel would be even a small fraction of the cost of all that machinery. Indeed, I found an article in which Musk states the fuel cost is 0.3% of the total launch cost:

So, clearly, wasting even a lot of something that is an infinitesimal part of the total cost, and one can imagine that even if this sacrifices payload capacity, at a 99.7% cost savings that can be made up on volume.

Although a rocket-powered tail-landing sure looks like a waste of fuel (and thus launch capacity), I suspect that pretty good proportion of the rocket's weight is fuel. Thus it might not take all that much fuel to land an empty rocket, compared to the fuel used for it's lifting purpose.

I'm not a rocket-scientist, and I haven't even done a back of the envelope calculation, but I wouldn't assume that they're doing something really inefficient unless there's evidence to the contrary.

Although a rocket-powered tail-landing sure looks like a waste of fuel (and thus launch capacity), I suspect that pretty good proportion of the rocket's weight is fuel. Thus it might not take all that much fuel to land an empty rocket, compared to the fuel used for it's lifting purpose.

I'm not a rocket-scientist, and I haven't even done a back of the envelope calculation, but I wouldn't assume that they're doing something really inefficient unless there's evidence to the contrary.

And beyond that, even if it proves impractical, sometimes things are worth just trying. Maybe the technique will prove inefficient for retreiving the engines, but yield results useful for space. Even if they decide it's ultimately a waste, there'll be a lot of data that may otherwise be useful.

I mean, perhaps landing the thing isn't cost-effective, but they learn techniques that make the rockets better able to correct their vector, meaning higher tolerance of things like wind speed for launches, which means less scrubbed launches and a longer launch window, ultimately reducing costs due to false starts.

Isn't it still much more expensive to land that thing than to just to let it burn up, or to retrieve it from the ocean?

You might be thinking of the Space Shuttle, which while "reusable" was wildly expensive to refurbish after each flight. (see Pompii's answer above about the cost of the workforce.) SpaceX's goal is not just achieve refurbish/reuse, but to achieve rapid and full reusability. Think of how a jetliner works. It'll be hard (launch and reentry is a seriously harsh environment), but it looks like they're getting closer to achieving it.

You might also be thinking of the necessary hit to payload-to-orbit that'll come with keeping enough fuel to fly back to the pad. Whether they can manage to create reusability hardware that's light enough to make the payload hit workable is one of the big question marks (launch and reentry already operates on razor-thin fuel margins), and I wouldn't say they've proven themselves yet. But they've sure gotten closer than anyone else.

Excellent, important question! I don't know why it's trending negative, and I only have one countervailing upvote to give it.

Wow, I am amazed that people suggesting the fuel costs less than the rocket are getting downvoted out of hand.

I didn't know the numbers, but it seemed absurd to suggest the fuel would be even a small fraction of the cost of all that machinery. Indeed, I found an article in which Musk states the fuel cost is 0.3% of the total launch cost:

So, clearly, wasting even a lot of something that is an infinitesimal part of the total cost, and one can imagine that even if this sacrifices payload capacity, at a 99.7% cost savings that can be made up on volume.

Payload capacity / weight / max altitude is the big deal not fuel costs lol. You lose in all three categories if you have to carry that extra fuel. It's an expensive trade off.

And they won't turn around and relaunch it without rather extensive survey of the rocket either

I find it odd too that they won't do a parachute to save weight. Maybe ars can do an interview?

Although a rocket-powered tail-landing sure looks like a waste of fuel (and thus launch capacity), I suspect that pretty good proportion of the rocket's weight is fuel. Thus it might not take all that much fuel to land an empty rocket, compared to the fuel used for it's lifting purpose.

I'm not a rocket-scientist, and I haven't even done a back of the envelope calculation, but I wouldn't assume that they're doing something really inefficient unless there's evidence to the contrary.

Yeah, it just looks so damn crazy it's hard to believe it is efficient or practical, but I have to assume that having come this far they at least believe this is a reasonable path of development.

Something that I read about the program that is really cool is that they are currently building this capability into all Falcon 9 rockets. They don't expect to successfully land one for some time, but each Falcon 9 launch will also serve as a test for the reusability program, so they will be amortizing the cost and risk of trying to make this work.

In this case the cost of fuel is ~ $200,000 dollars on a 60 million dollar piece of equipment. Reusability is something that has been touted as one of the benefits of the Space Shuttle. However it required a total overhaul to be launched again and the boosters and fuel tank were scrap after one use. If you are able to land the boosters and rocket and shave even 50% of the cost in restoration vs new the price of putting objects in orbit plummets.

Wow, I am amazed that people suggesting the fuel costs less than the rocket are getting downvoted out of hand.

I didn't know the numbers, but it seemed absurd to suggest the fuel would be even a small fraction of the cost of all that machinery. Indeed, I found an article in which Musk states the fuel cost is 0.3% of the total launch cost:

So, clearly, wasting even a lot of something that is an infinitesimal part of the total cost, and one can imagine that even if this sacrifices payload capacity, at a 99.7% cost savings that can be made up on volume.

Payload capacity / weight / max altitude is the big deal not fuel costs lol. You lose in all three categories if you have to carry that extra fuel. It's an expensive trade off.

And they won't turn around and relaunch it without rather extensive survey of the rocket either

I find it odd too that they won't do a parachute to save weight. Maybe ars can do an interview?

The big deal is total launch cost. And if you don't think they at least aspire to turn these things around within hours, you haven't been paying attention. Yes, it sounds insane after suffering the Shuttle program, but that's what they have in mind.

The DoD's DC/X did something similar in the '80s. It's amazing what the autopilot from an F-15 can do.

Then NASA took over the program and crashed it.

We won't get (relatively) cheap access to space until the vehicles are reusable. A ticket to fly from LA to Sydney, Australia isn't cheap, but imagine how expensive it would be if they pushed a 747 into the ocean after every flight.

People think simulations can calculate everything, but they're only as good as the data on which they're based. This is how we get the data.

To those asking about parachutes: parachutes are bulky and heavy. And not very maneuverable. SpaceX wants a soft landing in a precise location, and I assume they've done the weight calculations of parachutes vs. extra fuel.

Also, regarding the DCX/DCXA. Those were test bed vehicles that probably weren't terribly useful: low payload capacity, sub-orbital (at least for the experimental vehicle, plans were to scale it up in production). The cool thing about Grasshopper is that is essentially a 1st stage Falcon-9 tank. Grasshopper 2, scheduled to start testing at Spaceport America sometime between November-February, will be a much closer analog to the real launch vehicle, with all 9 engines and production landing gear. Much easier to transition to production than the DCX would have been.

To those asking about parachutes: parachutes are bulky and heavy. And not very maneuverable. SpaceX wants a soft landing in a precise location, and I assume they've done the weight calculations of parachutes vs. extra fuel.

Spot on. They also tried recovery with just parachutes on their first few launches, and it turns out that the passive stage basically belly-flops onto the atmosphere and crumples before the parachutes have a chance to do anything.

Wow, I am amazed that people suggesting the fuel costs less than the rocket are getting downvoted out of hand.

I didn't know the numbers, but it seemed absurd to suggest the fuel would be even a small fraction of the cost of all that machinery. Indeed, I found an article in which Musk states the fuel cost is 0.3% of the total launch cost:

So, clearly, wasting even a lot of something that is an infinitesimal part of the total cost, and one can imagine that even if this sacrifices payload capacity, at a 99.7% cost savings that can be made up on volume.

Payload capacity / weight / max altitude is the big deal not fuel costs lol. You lose in all three categories if you have to carry that extra fuel. It's an expensive trade off.

And they won't turn around and relaunch it without rather extensive survey of the rocket either

I find it odd too that they won't do a parachute to save weight. Maybe ars can do an interview?

They tried parachutes on the first gen Falcon 9, however because the vehicle was in free fall till there was enough air flow to use the parachutes, it put too much stress on the structure and broke up on re-entry on both tries. Being able to use the engine to slow it down and control it so it doesn't end up in an uncontrolled spin its possible will make this work. The first few launches of the new Falcon 9 plan to test some of concepts, such as relighting the engine and controlling the decent to a spot in the ocean, with the hope of using that info to work out making it back to the pad.

As it is, the new Falcon 9 v1.1 has about significantly more thrust, a larger first stage and more payload capacity so they will have more margin. Until they work out retrieving the first stage, they won't start work on second stage retrieval because that is way more difficult.

In this case the cost of fuel is ~ $200,000 dollars on a 60 million dollar piece of equipment. Reusability is something that has been touted as one of the benefits of the Space Shuttle. However it required a total overhaul to be launched again and the boosters and fuel tank were scrap after one use. If you are able to land the boosters and rocket and shave even 50% of the cost in restoration vs new the price of putting objects in orbit plummets.

tldr; Fuel is cheap.

Actually, NASA did reuse the solid rocket boosters (SRBs). They were made in sections stacked together, with gaskets between them. The Challenger exploded when one of the gaskets failed and heated up the external tank.

Chuck Yeager proposed they fix the problem by gluing them together permanently and not trying to reuse them. I bet it would have been cheaper, too.

To those asking about parachutes: parachutes are bulky and heavy. And not very maneuverable. SpaceX wants a soft landing in a precise location, and I assume they've done the weight calculations of parachutes vs. extra fuel.

Also, regarding the DCX/DCXA. Those were test bed vehicles that probably weren't terribly useful: low payload capacity, sub-orbital (at least for the experimental vehicle, plans were to scale it up in production). The cool thing about Grasshopper is that is essentially a 1st stage Falcon-9 tank. Grasshopper 2, scheduled to start testing at Spaceport America sometime between November-February, will be a much closer analog to the real launch vehicle, with all 9 engines and production landing gear. Much easier to transition to production than the DCX would have been.

Also, wasn't the DCX something like a tenth the size of Grasshopper? One thing that I tried to find but couldn't, is whether the DCX ever made any lateral flights like this. I don't think it ever did, but can anyone confirm or counter?

I took a semester of Control Systems in college, and it blows my mind that we can do this. Sensing pitch, roll rates and speed accurately enough and feeding it back to the engine gimbal to control the craft in a very maneuverable manner is no small feat.

The video is cool but to do this after first stage separation at about 4100 mph then return to the launch pad from a not insignificant lateral distance seems a bit much. The weight penalty, in needed return fuel, seems high to me.

Another question is are they going to shut all of the engines down at staging then restart the landing engines or suffer the problems they had with the Falcon 1 at staging?

So as of 18 months ago SpaceX's total investment was $1 billion. They've gotten this far, they have a capsule that can deliver supplies to the space station. They will have in-flight abort testing next year for the manned version.

When you look at the space shuttle, the total program cost was $1.3 billion per flight. SpaceX will have developed their whole rocket, capsule, and performed testing for what NASA spent to launch the space shuttle 3 times.

And now the company is performing commercial launches, which means its going to be making money on each launch.

You wonder why some people DONT want to continue government funding of certain things - because when the private sector does it, they do it better, faster, and cheaper.

In this case the cost of fuel is ~ $200,000 dollars on a 60 million dollar piece of equipment. Reusability is something that has been touted as one of the benefits of the Space Shuttle. However it required a total overhaul to be launched again and the boosters and fuel tank were scrap after one use. If you are able to land the boosters and rocket and shave even 50% of the cost in restoration vs new the price of putting objects in orbit plummets.

tldr; Fuel is cheap.

Actually, NASA did reuse the solid rocket boosters (SRBs). They were made in sections stacked together, with gaskets between them. The Challenger exploded when one of the gaskets failed and heated up the external tank.

Chuck Yeager proposed they fix the problem by gluing them together permanently and not trying to reuse them. I bet it would have been cheaper, too.

To those asking about parachutes: parachutes are bulky and heavy. And not very maneuverable. SpaceX wants a soft landing in a precise location, and I assume they've done the weight calculations of parachutes vs. extra fuel.

Also, regarding the DCX/DCXA. Those were test bed vehicles that probably weren't terribly useful: low payload capacity, sub-orbital (at least for the experimental vehicle, plans were to scale it up in production). The cool thing about Grasshopper is that is essentially a 1st stage Falcon-9 tank. Grasshopper 2, scheduled to start testing at Spaceport America sometime between November-February, will be a much closer analog to the real launch vehicle, with all 9 engines and production landing gear. Much easier to transition to production than the DCX would have been.

Also, wasn't the DCX something like a tenth the size of Grasshopper? One thing that I tried to find but couldn't, is whether the DCX ever made any lateral flights like this. I don't think it ever did, but can anyone confirm or counter?